Known as a conventional laser processing method is one comprising, as disclosed in Patent Literature 1, for example, converging a laser light into a silicon monocrystal substrate (object to be processed), so as to form a material transformed part (modified region), and then advancing etching along the material transformed part by etching the silicon monocrystal substrate, so as to remove the material transformed part and form a blind hole or through hole in the silicon monocrystal substrate.